Various conventional methods for ensuring the security of user data in cellular mobile radio networks exist. For example, the various mobile radio standards provide a number of functionalities for encrypting, and ensuring the integrity of, both user data and signaling data.
In current mobile radio systems such as UMTS (Universal Mobile Telecommunications System) and LTE (Long Term Evolution), there are a number of different encryption approaches which are typically used in all mobile radio networks. These include, inter alia, the mutual authentication of the terminal, that is to say the telecommunications terminal, with respect to the mobile radio network and of the mobile radio network with respect to the telecommunications terminal. These methods are also referred to using the keyword authentication. Encryption of the radio data transmission is provided between the telecommunications terminal (also referred to as the terminal below) and the radio network controller RNC for the case of a UMTS network and between the telecommunications terminal and the LTE base station (eNodeB). This encryption of the radio data transmission is also referred to using the keyword ciphering. Integrity of the radio data transmission is ensured between the telecommunications terminal and the radio network controller (RNC) and between the telecommunications terminal and the LTE base station (eNB). This is also referred to using the keyword integrity protection.
In conventional mobile radio systems such as the GSM system (Global System for Mobile Telecommunications) and UMTS, the radio protection (that is to say the encryption or guarantee of integrity) typically terminates in those network elements which are set up at a location which is not accessible to third parties, namely the base station system (BSS, Base Station Subsystem) or the radio network controller (RNC), in particular. This termination of the protection at locations which are not accessible to third parties is not the case according to the LTE standard because there the radio protection (that is to say the implementation of encryption and a guarantee of integrity) ends in the LTE base station, that is to say in the eNodeB, which need not necessarily be at a location which is inaccessible to third parties.
On account of a trend for making mobile radio network elements smaller and smaller, in particular using so-called femtocells or picocells, there is a tendency to install network elements at end customers. This does not ensure that third parties do not have physical access to such network elements, with the result that the risk of attacks on the data transmission is increased.